title: Fabrication of DNA nanowires by orthogonal self-assembly and DNA intercalation on a Au patterned Si/SiO2 surface.
abstract: A novel Ru complex bearing both an acridine group and anchoring phosphonate groups was immobilized on a surface in order to capture double-stranded DNAs (dsDNAs) from solution. At low surface coverage, the atomic force microscopy (AFM) image revealed the "molecular dot" morphology with the height of the Ru complex ( approximately 2.5 nm) on a mica surface, indicating that four phosphonate anchor groups keep the Ru complex in an upright orientation on the surface. Using a dynamic molecular combing method, the DNA capture efficiency of the Ru complex on a mica surface was examined in terms of the effects of the number of molecular dots and surface hydrophobicity. The immobilized surface could capture DNAs; however, the optimal number of molecular dots on the surface as well as the optimal pull-up speed exist to obtain the extended dsDNAs on the surface. Applying this optimal condition to a Au-patterned Si/SiO 2 (Au/SiO 2) surface, the Au electrode was selectively covered with the Ru complex by orthogonal self-assembly of 4-mercaptbutylphosphonic acid (MBPA), followed by the formation of a Zr (4+)-phosphonate layer and the Ru complex. At the same time, the remaining SiO 2 surface was covered with octylphosphonic acid (OPA) by self-assembly. The selective immobilization of the Ru complex only on the Au electrode was identified by time-of-flight secondary-ion mass spectrometry (TOF-SIMS) imaging on the chemically modified Au/SiO 2 surface. The construction of DNA nanowires on the Au/SiO 2 patterned surface was accomplished by the molecular combing method of the selective immobilized Ru complex on Au electrodes. These interconnected nanowires between Au electrodes were used as a scaffold for the modification of Pd nanoparticles on the DNA. Furthermore, Cu metallization was achieved by electroless plating of Cu metal on a priming of Pd nanoparticles on the Pd-covered DNA nanowires. The resulting Cu nanowires showed a metallic behavior with relatively high resistance.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan. mhaga@chem.chuo-u.ac.jp
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Naoya
authors.initials: N
authors.lastname: Tonegawa
authors.forename: Sho
authors.initials: S
authors.lastname: Fujii
authors.forename: Jiro
authors.initials: J
authors.lastname: Hikida
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Nozoye
authors.forename: Ken
authors.initials: K
authors.lastname: Tsutsui
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Wada
authors.forename: Makoto
authors.initials: M
authors.lastname: Chikira
authors.forename: Masa-Aki
authors.initials: MA
authors.lastname: Haga
mesh_terms: D004247:DNA / Q000737:chemistry*; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D007364:Intercalating Agents / Q000494:pharmacology; D013058:Mass Spectrometry / Q000379:methods; D008670:Metals / Q000737:chemistry; D018625:Microscopy, Atomic Force; D053761:Nanocomposites / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D063065:Organophosphonates / Q000494:pharmacology; D010165:Palladium / Q000737:chemistry; D010647:Phenyl Ethers; D011422:Propionates / Q000737:chemistry; D012825:Silicon / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D015040:Zirconium / Q000737:chemistry
chemical_list: C118761:3-(4-methoxybenzoyl)propionic acid; D007364:Intercalating Agents; D008670:Metals; D063065:Organophosphonates; D010647:Phenyl Ethers; D011422:Propionates; D010165:Palladium; D006046:Gold; D012822:Silicon Dioxide; D004247:DNA; D015040:Zirconium; D012825:Silicon